Such a unitary suspension device is described in the patent application published under the No. FR 2 824 246 in the name of the Applicant. That device comprises a base element fixed on an element of a platform, a suspension structure fixed on the base element, and a top plate carried by the suspension structure and fastened thereon by a quarter-turn fastener device.
The unitary suspension devices are disposed in rows and columns on the platform, and the generally rectangular top plates are disposed in a common plane so as to constitute a checkerboard or matrix configuration. These top plates are spaced apart from one another by gaps having a width lying in the range 1 centimeter (cm) to 4 cm.
In general, the top plates are plane. In FIGS. 2 and 8, FR 2 824 246 shows top plates having the shape of flat dinner plates and, in FIG. 28, it shows a top plate whose edges flare slightly downwards.
Those top plates are in contact with the mattress and they extend above the platform like studs that are separated from one another or like paving stones that are poorly jointed.
Those top plates give the impression of being insufficiently strong if they are made of plastic, and an impression of being too rigid if they are made of wood, whereas the bulking of the padding under the mattress gives an impression of comfort.